Flexible tubing occlusion assembly

ABSTRACT

An occlusion assembly for compressing a pair of collapsible tubes comprises a frame comprising a tubing guide configured for positioning the collapsible tube. The occlusion assembly also comprises a tubing occluder mounted to the frame with an occluding member constructed and positioned to controllably occlude or release occlusion of the collapsible tube. A door mounted to the frame is positioned to cover at least a portion of the collapsible tube and tubing occluder when closed and provide user access when open. The assembly includes a retainer mechanism engaged by the door when the door is closed to permit operation of the tubing occluder when the door is closed and retain the tubing occluder in a non-occluding configuration when the door is opened.

RELATED APPLICATIONS

This application is a division of U.S. patent application Ser. No. 15/181,234, filed Jun. 13, 2016, and issued on Jul. 11, 2017, as U.S. Pat. No. 9,700,711, which is a division of U.S. patent application Ser. No. 13/480,236, filed May 24, 2012, and issued on Jun. 14, 2016, as U.S. Pat. No. 9,364,655, all of which are incorporated herein by reference in their entireties.

FIELD

The present specification generally describes occluder devices for occluding flexible tubing, particularly in medical infusion systems.

BACKGROUND

Medical devices, such as hemodialysis machines, medical infusion pumps, plasmapheresis devices, and the like, often require the use of tubing to facilitate the flow of fluids, e.g., to or from a patient using such device. Such tubing in many instances is made of a flexible material and is designed to be collapsible in order to facilitate peristaltic pumping and/or occlusion of fluid flow via collapse of the lumen of the flexible tubing. A variety of tubing clamps and tubing occlusion devices are known. Certain of these devices can be integrated into a medical infusion device and automatically controlled. In certain applications, medical infusion devices must handle fluids that include ingredients that, due to leakage or other factors that may lead to presence of the fluid on the external surfaces of the tubing, can become sticky and or result in fouling or failure of certain conventional tubing occluder designs.

SUMMARY

Described herein are occlusion assemblies configured to facilitate the opening and closing by occlusion of flexible tubing. In particular embodiments, the occlusion assemblies are associated with or form part of a medical infusion device, such as a hemodialysis device, peritoneal dialysis device, plasmapheresis device, etc., and may be controllably and automatically operated to facilitate fluid handling by such devices. The occlusion assemblies may be designed to position and immobilized the tubing and may include a frame or other support feature providing tubing guides and/or configured for attachment to or integration with a fluid handling assembly of a device of which they are part or with which they are used. The occlusion assemblies comprise a tubing occluder, which may be a mechanism constructed and positioned to apply a force to the tube(s) associated with the occlusion assembly to occlude the tubes and to release the force to allow the tubes to open for fluid flow. The occlusion assemblies and tubing occluders may be configured to include a single tube in certain cases, and in other cases to occlude multiple tubes, whether an odd number of tubes or an even number of tubes. Certain occlusion assemblies are specifically configured for occluding one or more pairs of tubes and may include tubing occluders having a separate occluding member for occluding each of the pair of collapsible tubes. The occlusion assemblies may include automatic actuators for operating the tubing occluders, and in certain cases also include a manual actuator to provide an override function. The occlusion assemblies may include a door designed and positioned to cover at least a portion of the tubes to be occluded and tubing occluder mechanism. Such occlusion assemblies may include safety features, for example, to prevent a release of occlusion force on the tubing when the door is not in a closed position and/or convenience features, for example a retainer mechanism to hold the tube occluder in a non-occluding position when the door is open with the tube occluder in the non-occluding position.

In one aspect, a variety of occlusion assemblies for occluding at least one collapsible tube of a medical infusion device are described. In certain embodiments, the occlusion assembly is configured for occluding at least one pair of collapsible tubes and comprises, for each pair of collapsible tubes, a first occluding member and a second occluding member, the first occluding member positioned adjacent to a first collapsible tube of the pair and the second occluding member positioned adjacent to a second collapsible to the pair, when the tubes are installed in the occlusion assembly for operation. The first occluding member and the second occluding member are further positioned adjacent from each other such that a space is defined between them. These space is on an opposite side of each occluding member then is the collapsible tube to which it is adjacent. The occlusion assembly further comprises a spreader positioned within the space between the occluding members and movable from a first position to a second position, wherein movement from the first position to the second position causes the spreader to force at least a portion of the first and second occluding members to move apart from each other to increase the size of the space between them and forced a tube-contacting portion of each occluding member against the collapsible tube to which it is adjacent to occlude the collapsible tube. The occlusion assembly further comprises at least one actuator constructed and positioned to move the spreader between the first and second positions.

In certain embodiments the occlusion assembly is configured for occluding at least one collapsible tube and comprises a frame comprising a tubing guide configured for positioning the collapsible tube, a tubing occluder mounted to the frame and comprising an occluding member constructed and positioned to controllably occlude or release occlusion of the collapsible tube, a door hingeably mounted to the frame and positioned to cover at least a portion of the collapsible tube and tubing occluder when in a closed position and to provide user access to the collapsible tube when in an open position, and a switch configured and positioned to detect when the door is in a closed position and to permit operation of the tubing occluder to release occlusion of the collapsible tube only when the door is in the closed position.

In certain embodiments and occlusion assembly for collapsing at least one collapsible tube comprises a tubing occluder comprising an occluding member constructed and positioned to controllably occlude or release occlusion of the collapsible tube, and automatic actuator operatively coupled to the tubing occluder to cause essentially linear motion of at least a portion of the tubing occluder to cause the occluding member to move from an occluding position to a non-occluding position, and an override mechanism operatively coupled to the tubing occluder to cause essentially linear motion of at least a portion of the tubing occluder to cause the occluding member to move from an occluding position to a non-occluding position upon manual operation of the override mechanism by a user.

In certain embodiments, and occlusion assembly for occluding at least one collapsible tube comprises a frame comprising a tubing guide configured for positioning the collapsible tube, a tubing occluder mounted to the frame and comprising an occluding member constructed and positioned to controllably occlude or release occlusion of the collapsible tube, a door hindgeably mounted to the frame and positioned to cover at least a portion of the collapsible tube and tubing occluder when in a closed position and to provide user access to the collapsible tube when in an open position, and a retainer mechanism engaged by the door when the door is in the closed position and configured to permit operation of the tubing occluder to occlude or release occlusion of the collapsible tube when the door is in the closed position and configured to engage and retain the tubing occluder in a non-occluding configuration when the door is opened while the tubing occluder is positioned in the non-occluding configuration.

In another aspect a method of operating an occlusion assembly for occluding at least one pair of collapsible tubes of a medical infusion devices disclosed. In one embodiment, the method involves moving a spreader of the occlusion assembly from a first position to a second position, wherein the spreader is positioned within a space defined between a first occluding member and a second occluding member to cause the spreader to force at least a portion of the first and second occluding members to move apart from each other to increase the size of the space between them and force a tube-contacting portion of each occluding member against a collapsible tube to which it is adjacent to occlude the collapsible tube.

Other advantages and novel features of the present invention will become apparent from the following detailed description of various non-limiting embodiments when considered in conjunction with the accompanying figures. In cases where the present specification and a document incorporated by reference include conflicting and/or inconsistent disclosure, the present specification shall control.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are schematic are not intended to be drawn to scale. In the figures, each identical, or substantially similar component that is illustrated in various figures is typically represented by a single numeral or notation. For purposes of clarity, not every component is labeled in every figure, nor is every component of each embodiment of the invention shown where illustration is not necessary to allow those of ordinary skill in the art to understand the invention. In the drawings:

FIG. 1 shows an exploded, perspective view of an occlusion assembly from a front angle in accordance with an embodiment of the present disclosure;

FIG. 2 shows an exploded, perspective view of the occlusion assembly of FIG. 1 from a back angle;

FIG. 3 shows a front, perspective view of the occlusion assembly of FIG. 1 with the door open and the button pressed to illustrate loading of a tube;

FIG. 4 shows a close-up perspective view of the occlusion assembly of FIG. 1, showing the door engaging a switch when the door is closed;

FIG. 5 shows the front of the occlusion assembly of FIG. 1 without the door and frame to illustrate the arms fully occluding flexible tubes;

FIG. 6 shows the front of the occlusion assembly of FIG. 1 without the door and frame to illustrate the arms in a non-occluding position;

FIG. 7 is a rear/top perspective view of the occlusion assembly of FIG. 1 with an actuator arm in a fully retracted position;

FIG. 8 is a rear perspective view of the occlusion assembly of FIG. 1 with an actuator arm in a fully extended position;

FIG. 9 shows a side perspective view of several working parts of the occlusion assembly of FIG. 1 in a non-occluding state;

FIG. 10 shows a side perspective view of several working parts of the occlusion assembly of FIG. 1 in an occluding state;

FIG. 11 shows a side, cross-sectional view of an actuator of the occlusion assembly of FIG. 1, illustrating a location for a main spring for the assembly; and

FIG. 12 shows the occlusion assembly of FIG. 1 mounted in a front panel assembly of a hemodialysis apparatus in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION

In accordance with one aspect of the disclosed invention, an occlusion assembly for compressing at least one flexible tube, for example a pair of flexible tubes is described. The occlusion assembly includes a tube occluder comprising a mechanism configured to occlude fluid flow within one or more flexible tubes, and in certain embodiments one or more pairs of flexible tubes. In certain embodiments, the tube occluder of the occlusion assembly comprises at least one occluding member, and in a specific embodiment comprises an occluding member for each section of tubing placed within the assembly. In certain such embodiments, each occluding member is pressed or otherwise forced or urged into an occluding position by an element that slides along a side of the occluding member, causing the occluding member to pivot at its proximal end and to translate toward the tubing at its distal end. In an embodiment, the element is positioned between two occluding members and acts to spread the distal ends of the occluding members away from each other as they press against their respective tubes. In a preferred option, a main spring urges the spreading element toward the distal ends of the occluding elements into an occluding position. The spreading element may be moved against the biasing force of the main spring into a non-occluding position near the proximal ends of the occluding elements either manually through a button and linkage assembly coupled to the spreading element, or by control of a controller activating an actuator that is also coupled to the spreading element. A hinged door may be configured to cover the occluding elements and their respective sections of tubing. Activation of the actuator may be prevented if the door is not properly closed over the occluding elements. Optionally, a retention element to hold the spreading element in a non-occluding position may be enabled when the door is in an open position. Enabling the retention element allows the spreader to be held in a non-occluding position without continued application of force by a user on the button or by continued activation of the actuator. The retention element may be disabled when the door is closed, so that the spreading element may be free to be moved into and out of an occluding position, either manually or via the actuator.

FIGS. 1 and 2 show exploded, perspective views of an occlusion assembly 700 in accordance with an embodiment of the present disclosure. FIG. 1 shows an exploded, perspective view of the occlusion assembly 700 from a front angle and FIG. 2 shows an exploded, perspective view of the occlusion assembly 700 from a back angle.

The occlusion assembly 700 receives a pair of tubes 705 and is configured to occlude the tubes 705 using a pinching action at approximately the same level along the length of assembly 700. The pinching action reduces the size of an inner fluid pathway of each tube 705 to restrict the flow of fluid therethrough. The occlusion assembly 700 may be used with an infusion pump, in a dialysis machine, in hemodialysis, in peritoneal dialysis, in hemofiltration, in hemodiafiltration, in intestinal dialysis, and the like.

The occlusion assembly 700 includes a frame 701. In some embodiments, the frame 701 includes tabs or snaps 709 for securing the frame to corresponding slots on a front panel of a blood filtration device, such as a hemodialysis apparatus.

The frame 701 includes anvils or blocks 702 and 703 against which a tube 705 is compressed by the occluding ends 713 of a pair of occluding arms 710 and 711, and a tube guide 704 to position each tube 705 against blocks 702 and 703. The tube guide 704 and blocks 702 and 703 are configured to each position a tube 705 in a predetermined position adjacent to each of the blocks 702 and 703. The occlusion assembly 700 also includes a door 706 which is pivotally mounted to the frame 701. The door 706 can shut against the frame 701 to secure the tubes 705 between each of the blocks 702 and 703 and the tube guide 704. The door 706 includes a latch 707, which may be co-molded with or otherwise attached to the door 706 via a hinge, such as for example a resilient, flexible base portion (e.g., via a living hinge) 708 to secure the door 706 to the frame 701 in a closed position. As shown in FIGS. 1, 3, and 4, a latch 707 may be pressed laterally to release a catch 740 from engagement with a corresponding slot 741 on frame 701 to open the door 706.

The occlusion assembly 700 includes two arms 710 and 711. The first arm 710 includes a pivoting end 712 and an occluding end 713; likewise, the second arm 711 includes a pivoting end 714 and an occluding end 715. The two arms 710 and 711 operate together to occlude the tubes 705 when a manual actuator, such as button 716, is released (or in other embodiments engaged) and door 706 is closed, or when an actuator 717 is deactivated

FIG. 3 shows a front, perspective view of the occlusion assembly 700 with the door 706 open and the button 716 pressed to illustrate release of occluding arms 710 and 711 to permit loading and unloading of the tubes 705 in accordance with an embodiment of the present disclosure. FIG. 5 shows the front of the occlusion assembly 700 of FIG. 1 without the door 706 and frame 701 to illustrate the arms 710 and 711 fully occluding the tubes 705 a, b in accordance with an embodiment of the present disclosure. As shown in FIG. 5, a wedge element or spreader 722 contacts the facing sides of occluding arms 710 and 711, which under spring force can apply pressure to occluding arms 710 and 711 to press the occluding ends 713 and 715 of occluding arms 710 and 711 against a portion of tubes 705 a, b. A user may release the occluding arms 710 and 711 by pressing button 716, which causes spreader 722 to withdraw away from occluding arms 710 and 711, releasing the pressure of spreader 722 being applied to the distal ends of occluding arms 710 and 711. In some aspects, the manual actuator (e.g. button 716) acts as an override mechanism to an automated actuator (such as, for example, a pneumatically operated piston/cylinder apparatus) connected to a tubing occluder element (e.g., the spreader 722). The manual actuator is operatively coupled to the tubing occluder to cause essentially linear motion of at least a portion of the tubing occluder, moving the occluding member from an occluding position to a non-occluding position upon manual operation of the override mechanism by a user.

Similarly, activation of an actuator may release occluding arms 710 and 711 by causing spreader 722 to withdraw away from the occluding ends 713, 715 of occluding arms 710 and 714. In one embodiment, as shown in FIG. 1, spreader 722 may be formed of, co-molded with, attached to or connected to a carriage assembly 723, which in turn is connected to an actuating arm of the actuator (see, e.g., FIGS. 7-9). The actuator may comprise, for example, a motor and gear assembly (e.g., rack and pinion assembly or worm-type gear assembly), a solenoid, a hydraulic cylinder or a pneumatic cylinder, among others. In a preferred embodiment, the actuator comprises a pneumatic cylinder 717 that causes an actuating arm comprising a piston arm 742 to extend linearly against a spring force (which in an embodiment may be a coil spring 745 within cylinder 717 as shown in FIG. 11). As shown in FIG. 11, in a perspective side view of a pneumatically operated linear actuator 717, piston arm 742 is connected to carriage 723. When activated by pneumatic pressure, actuator 717 extends piston arm 742 and moves carriage 723 and attached spreader 722 in a direction that withdraws spreader 722 from engagement with the distal ends 713, 715 of the occluding arms 710 and 711. (For clarity, occluding arm 711, frame 701, door 706, block 703 and tube guide 704, among other elements, have been removed from FIGS. 9-11). Preferably, a main spring that is either external or internal to cylinder/actuator 717 may apply a biasing force to piston arm 742 or carriage 723 to cause spreader 722 to move occluding arms 710 and 711 to an occluding position. In the event of a loss of power or pneumatic pressure, the occluding arms 710 and 711 will default to an occluding mode, preventing the flow of fluid through tubes 705. As illustrated in a cross-sectional view of occlusion assembly 700 in FIG. 11, in an embodiment, a coil spring 745 may be placed within the cylinder 743 to provide a biasing force against which piston 744 may move piston arm 742 under pneumatic pressure. Pneumatic pressure may be supplied to linear actuator 717 from a pressure source (e.g., a tank pressurized by a pump) regulated by an intervening electromechanical valve under control of an electronic controller.

As shown in FIGS. 5 and 10, when the linear actuator 717 is fully retracted, the carriage 723 carries spreader 722 along the facing sides of the occluder arms 710 and 711 to rotate them into an occluding position. The first arm 710 pivots about its pivoting end 712 to cause the occluding end 713 to press against first tube 705 a that is restrained by block 702 (see FIG. 5). The second arm 711 pivots about its pivoting end 714 such that the occluding end 715 can press against second tube 705 b which is restrained by block 703.

FIGS. 6 and 9 show occlusion assembly 700 in a non-occluding state (frame 701, door 706, blocks 702, 703, and other elements removed for clarity). When the button 716 is pressed or the linear actuator 717 is activated, the carriage 723 and attached spreader 722 move distally away from the actuator 717, allowing occluder arms 710 and 711 to rotate about pivot points 712 and 714 into a non-occluding position. The elastic resilience of the tubes 705 a.b may cause the arms 710 and 711 to pivot towards each other. In some embodiments of the present disclosure, small magnets (not explicitly shown) embedded in the arms 710 and 711 pull the arms 710 and 711 towards each other to facilitate the retraction of the occluding ends 713 and 715 away from the tubes 705. In other embodiments, small springs (not shown) may bias occluding arms 710 and 711 to pivot toward each other, the spring constants being weak enough to be overcome by the main spring (e.g., spring 745) biasing carriage 723 or spreader 722 into retracted (occluding) positions.

FIG. 4 shows a perspective side view of the occlusion assembly 700 of FIG. 1(frame 701 removed for clarity) showing the door 706 engaging a switch 720 when the door 706 is closed in accordance with an embodiment of the present disclosure. As shown in FIG. 4, the hinge portion 708 of latch 707 is coupled to an engagement member or catch 740 that can snap into a cooperating slot 741 of the frame 701 (see, e.g., FIGS. 1 and 3). As the door 706 is closed, a portion of the catch 740 of latch 707 of the door 706 engages a spring-loaded switch 720, which in an embodiment includes a spring arm 737 of the switch 720.

Engagement of switch 720 by closure of door 706 signals an electronic controller (not shown) that the door 706 is properly closed, and that linear actuator 717 may be activated to release occluders 710 and 711 to allow fluid to flow through tubes 705. The door 706 closure signal may also cause the controller to perform other functions, such as, for example, instructing a pump coupled to the tubes 705 to begin pumping fluid within tubes 705.

FIG. 7 shows the back of the occlusion assembly 700 of FIG. 1 with the linear actuator 717 in a fully retracted position (i.e., in the occluding position) in accordance with an embodiment of the present disclosure. FIG. 7 shows the back side of the occlusion assembly 700 in the same configuration as shown for the front view of occlusion assembly 700 in FIG. 5. FIG. 7 shows several working parts of the occlusion assembly 700 of FIG. 1 to illustrate the operation of the actuator 717 and carriage 723 in accordance with an embodiment of the present disclosure. The carriage 723 moves with the extension or retraction of the piston arm 742 or with the actuation of the button 716. The carriage 723 includes guides 724 attached to or co-molded with the carriage 723. The guides 724 guide the carriage 723 as it moves via actuation of the piston arm 742 or with the actuation of the button 716. The guides 724 interface with tracks 725 of the frame 701 (see, e.g., FIG. 2).

In an optional embodiment, when door 706 is open, actuation of button 716 by a user or activation of actuator 717 by a controller causes carriage 723 and spreader 722 to move into a non-occluding position, and a retaining element or assembly allows the non-occluding position to be held without further force being applied either by the user or by the actuator 717. In an exemplary embodiment shown in FIG. 7, the carriage 723 may incorporate a latching pin 726 to cooperate with a slot or hole in a retention member 718. The retention member 718 includes a surface 727 positioned to be contacted by pins 738 located on the inside of door 706 when it is closed (see, e.g., FIGS. 2 and 3). Through holes 739 (see, e.g. FIGS. 1 and 3) allow pins 738 to contact a portion of retention member 718 to displace it in a rearward direction. In the illustrated embodiment, pins 738 contact front plate 727 of retention member 718. Retention member 718 also includes a surface having a slot or hole 729 positioned to receive the head of a latching pin 726, which in the illustrated embodiment comprises a horizontal plate 728 defining a receiving portion 729. Retention member 718 is arranged to slide within grooves or guides of the frame 701 (not shown) in response to contact by the pins 738 when the door 706 is closed or opened (see, e.g. FIG. 2). A spring 730 mounted on the frame 701 may be biased to urge the retention member 718 forward to a stop feature (not shown) on the frame 701 so that opening the door 706 allows the retention member 718 to slide forward, re-aligning the receiving portion 729 in relation to the latching pin 726. When the door 706 is closed (see FIG. 1 or 2), the pins 738 on the door 706 press against the front plate 727 which compresses the spring 730 such that the receiving portion 729 of the horizontal plate 728 is positioned directly over the latching pin 726. Upon alignment of the receiving portion 729 with the latching pin 726, the area of the receiving portion 729 is large enough to allow the latching pin 726 to be released by the retention member 718, thereby allowing the carriage 723 to be subject to the spring force of the main spring 745 in the actuator 717. If pneumatic pressure is not then being applied to the actuator 717, the carriage 723 is then free to move into an occluding position. The retention member 718 in the disabled state (i.e., inoperative state) allows the latching pin 726 to move freely through the receiving portion 729 as the carriage 723 moves between the fully extended position and the fully retracted position.

FIG. 8 is a rear view of the occlusion assembly 700 with the actuator 717 activated, and the piston arm 742 in an extended position to place the occluding arms 710, 711 in a non-occluding state. In this view, the head of the latching pin 726 is noted to be above the plane of the horizontal plate 728 of the retention member 718, and the recessed region 731 of the latching pin 726 is noted to be aligned with the receiving portion 729 of the retention member 718. In this illustration, door 706 is in a closed position, implying that the receiving portion 729 is in a sufficiently rearward position to prevent the latching pin 726 from being latched into the retention member 718.

When the door 706 is sufficiently opened, the pins 738 of the door 706 do not press against the front plate 727 and the spring 730 applies a force on the front plate 727 such that the receiving portion 729 of the retention member 718 is positioned to allow the latching pin 726 to engage an edge of the receiving portion 729 and latch to the retention member 718. The latching pin 726 moves into the receiving portion 729 pulling the front plate 727 rearward against the force of the spring 730 when the receiving portion 729 is positioned to latch to the latching pin 726. When the head of latching pin 726 moves sufficiently through the receiving portion 729, a recessed region 731 below the head of latching pin 726 becomes co-aligned with the horizontal plate 728 which moves as the edge of the receiving portion 729 moves into the recessed region 731 under the force of the spring 730 as applied to the front plate 727. When the pins 738 of the door 706 sufficiently engage the front plate 727, the receiving portion 729 is positioned to release the latching pin 726 from the latch 718. Thus, when the door 706 is open, the carriage 723 and spreader 722 can be held in a non-occluding position without the continuous application of force by the actuator 717 or by a user pressing against the button 716. This permits a user to load and unload tubing from occlusion assembly 700 without simultaneously having to apply force on the button 716. However, upon the closing of the door 706, the retention member 718 is no longer operative, and in the absence of continued application of force by either the actuator 717 or through the button 716, the carriage 723 and spreader 722 will move into a position to cause the occluding arms 710 and 711 to rotate to an occluding position.

FIGS. 9 and 10 show a side perspective view of several working parts of the occlusion assembly 700 of FIG. 1, with frame 701, blocks 702, 703, tube guide 704, door 706, occluding arm 711 and other parts removed for clarity. In FIG. 9, the piston arm 742 is fully extended in accordance with an embodiment of the present disclosure. FIG. 9 shows the latching pin 726 latched onto the retention member 718. That is, assuming that door 706 is in an open position, the horizontal plate 728 is positioned by the force of spring 730 to engage the recessed region 731 of the latching pin 726.

FIG. 10 shows a side, perspective view of the occlusion assembly 700 of FIG. 1 with the piston arm 742 in a fully retracted position, with certain elements removed as in FIG. 9 for clarity. In this example, the latching pin 726 is shown to be completely disengaged from the retention member 718; and in the absence of an activating force on the actuator 717 or a pressing force on the button 716, the piston arm 742, carriage 723 and spreader 722 are free to retract under the force of a main spring 745 (see FIG. 11) biased against the extension of piston arm 742. The spreader 722 then moves toward the occluding ends 713, 715 of the occluding arms 710, 711. In an embodiment, as shown in FIGS. 9 and 10, the button 716 pivots about a pivot 732 to raise a lever arm 733 when the button 716 is pressed. The lever arm 733 is pivotally connected to a connecting member 734 via a proximal pivot 735. The connecting member 734 in turn is pivotally connected to the carriage 723 via a distal pivot 736. When the button 716 is pressed or the piston arm 742 moves the carriage 723 toward the retention member 718, the connecting member 734 moves with the carriage 723, rotating the button 716 about the pivot 732 as shown in FIG. 9.

FIG. 12 shows the occlusion assembly 700 of FIG. 1 used in a front-panel assembly 911 of a dialysis system in accordance with an embodiment of the present disclosure. The occlusion assembly 700 occludes flexible tubes 901, 902 through which blood flows to and from a patient. The right side tube 902 carries blood from a patient into a blood pump assembly 1000 and the left side tube 901 carries blood from a dialyzer 14 back to the patient after passing through an air trap 19. The occlusion assembly 700 can occlude the flow of blood through both of these patient tubes 801, 802 simultaneously.

The tubes 901, 902 are connected to a blood pump cassette or assembly 1000. The blood pump cassette 1000 is a modular unit that may be mounted onto and dismounted from the front-panel assembly 911. Both of the patient tubes 901, 902 may be provided as an assembly with the blood pump cassette 1000 and air trap 19, and may be loaded into the occlusion assembly 700 when the blood-pump cassette 1000 is mounted onto the front-panel assembly 911. In this embodiment, the occlusion assembly 700 forms a permanent part of the front panel assembly 911.

When the occlusion assembly 700 is in the non-occluding state, pumps located on blood pump cassette 1000 may be activated to pump blood from a patient through the right tube 902, up through the blood pumps and through a dialyzer 14. Blood processed by the dialyzer 14 then returns to the patient via tube 901 after first passing through an air trap 19 and an air-in-line detector 823.

While several embodiments of the invention have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other means and structures for performing the functions and/or obtaining the results or advantages described herein, and each of such variations, modifications and improvements is deemed to be within the scope of the present invention. More generally, those skilled in the art would readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that actual parameters, dimensions, materials, and configurations will depend upon specific applications for which the teachings of the present invention are used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. It is, therefore, to be understood that the foregoing embodiments are presented by way of example only and that, within the scope of the appended claims and equivalents thereto, the invention may be practiced otherwise than as specifically described. The present invention is directed to each individual feature, system, material and/or method described herein. In addition, any combination of two or more such features, systems, materials and/or methods, provided that such features, systems, materials and/or methods are not mutually inconsistent, is included within the scope of the present invention. 

What is claimed: 1-4. (canceled)
 5. An occlusion assembly for occluding at least one collapsible tube of a medical infusion device, comprising: a frame comprising a tubing guide configured for positioning the collapsible tube; a tubing occluder mounted to the frame and comprising an occluding member constructed and positioned to controllably occlude or release occlusion of the collapsible tube; a door hingeably mounted to the frame and positioned to cover at least a portion of the collapsible tube and tubing occluder when in a closed position and to provide user access to the collapsible tube when in an open position; and a retainer mechanism engaged by the door when the door is in the closed position and configured to permit operation of the tubing occluder to occlude or release occlusion of the collapsible tube when the door is in the closed position and configured to engage and retain the tubing occluder in a non-occluding configuration when the door is opened while the tubing occluder is positioned in the non-occluding configuration. 6-15. (canceled)
 16. The occlusion assembly of claim 5, wherein the tubing occluder comprises a carriage assembly slidably mounted to the frame, and wherein the carriage assembly i. is operatively coupled to an actuator that is configured to cause sliding motion of the carriage assembly, ii. is operatively coupled to an occluding member engaging element configured to move the occluding member into an occluding position or permit the occluding member to move into a non-occluding position upon sliding motion of the carriage assembly, iii. comprises a latching pin.
 17. The occlusion assembly of claim 16, further comprising a retention member movably mounted to the frame, the retention member comprising a surface configured and positioned to be engaged by a portion of the door when the door is in the closed position, the retention member further comprising a latching pin receiving hole sized and positioned to allow substantially unrestricted entry of the latching pin into the latching pin receiving hole upon sliding motion of the carriage assembly in a direction to permit the occluding member to move into the non-occluding position and exit of the latching pin from the latching pin receiving hole upon sliding motion of the carriage assembly in a direction move the occluding member into the occluding position when the door is in the closed position, wherein the retention member is biased for movement upon opening of the door to cause the latching pin receiving hole to move into engaging and retaining contact with the latching pin when the carriage assembly is positioned in its non-occluding position when the door is open. 18-20. (canceled) 